Not applicable.
Not applicable.
The present invention relates to novel microorganisms and relates, in particular, to a novel archaeal microorganism which is an extremophile.
Microorganisms including both bacteria and archaeal species populate a wide variety of environmental niches throughout the planet earth. It is now known that microorganisms exist in the air, under the ocean, and even, perhaps, in subsurface geologic formations. The extent to which microorganisms have colonized and adapted for unique ecology niches is something that has only recently begun to be understood by microbiologists.
One category of microorganisms that has begun to receive some attention are those known as extremophiles. This term, perhaps not truly a rigorous scientific term, refers to microorganisms that have evolved to exist in ecological niches in which they are commonly exposed to environmental conditions which would have been thought, not very many years ago, to be too extreme to support living organisms. An example of entire ecological niches based on extremophiles has been discovered in sulfite metabolizing organisms which exist at the bottom of ocean trenches and derive their energy from geological rather than solar forces.
The modern biotechnology industry has come to understand that extremophiles represent a potential for biological prospecting for novel enzymes, sometimes referred to as extremozymes. Since a living organism is required to maintain its set of housekeeping enzymes in order to live and thrive, it naturally follows that an extremophile existing in a hostile environment has evolved enzymes which are capable of performing their appropriate catalytic activity under the conditions which the microorganism lives. If one looks at an organism which exists natively in a given environment that approximates the needs of an industrial process, it becomes possible to look for enzymes capable of catalyzing a needed reaction under the conditions existing in the corresponding industrial process. One well known example of this is the DNA polymerase from the organism Thermus aquaticus, which was originally isolated from a hot spring. The Thermus aquaticus DNA polymerase, referred to as Taq polymerase, is now widely used in the genetic engineering field, particularly in the performance of the PCR and DNA sequencing reactions, due to its thermal stability. The thermal stability of the polymerase was necessary in the native Thermus aquaticus, because its environment was a hot spring which natively exposed the host microorganism to exceedingly high temperatures.
Other extremophiles have been isolated which are heat tolerant thermophiles, cold tolerant psychrophiles, acid tolerant acidophiles, alkaline tolerant alkaliphiles, and salt tolerant halophiles.
One extremely hostile environment occurs where waste water pools emanate from iron mines. Iron is often found in geologic formations in the form of iron pyrite, and the interaction between materials such as sulfites, such as pyrite, water, microorganisms and air results in very acidic and metal rich waters. The accumulation of such acidic metal rich waters is accelerated by mining activities and results in a form of pollution acid mine drainage. However, sulfite solutions occur: naturally in the absence of mining, even though the human impact can enhance its accumulation.
Previous studies have suggested the role of some microorganisms in the processing and cycling of metals in acid mine drainage. In particular, the iron-oxidizing bacterium Thiobacillus ferrooxidans was thought to be the most important oxidizing species in acid mine drainage. However, later work has suggested that archaeal species may be more abundant than bacterial species in at least some important sites of acid mine drainage generation during at least the dry summer and fall months. Edwards et al., Geomicrobiology Journal 16: 155-179 (1979). To date the archaeal species present at such sites have not been characterized or cultured.
It is reported here that a novel archaeal species has been identified in an acid mine drainage site. The isolate is a novel iron-oxidizing archaeal species that is capable of growth at extraordinarily low levels of pH, down to a pH of 0. The organism is abundant and even predominant in solutions of high conductivity and low pH. The organism is referred to here by a coined, but unofficial, species designation of Ferroplasma acidarmanus. 
It is an object of the present invention to contribute to the knowledge of mankind the existence of a novel archaeal species that is more acid tolerant than other previously known species.
It is another object of the present invention to identify, culture and make available an organism which possesses, at a minimum, metal oxidizing and cell surface proteins and enzymes which have extreme tolerance to conditions of very low pH.
It is a further object of the present invention to describe a microorganism which is extremely tolerant of both low pH and high concentrations of.metals which might be toxic to less hardy strains or species, thus providing a biological platform for potential genetic engineering of organisms which can thrive in hostile environments.
Other objects, advantages and features of the present invention become apparent from the following specification when taken in conjunction with the accompanying drawings.